This invention relates to film fill sheets making up fill packs used in liquid cooling apparatus, and especially to film fill sheets each having repeating, successive surface area-increasing patterns. The film fill sheets are each configured to be arranged in a shingled bundle in nested relationship for shipping. The shingled bundle may be mounted as a unit on the support structure for the fill pack in the cooling tower apparatus. Thereafter, the bundle may be expeditiously expanded in place by effecting relative movement between the sheets while supported by the support structure to unshingle the bundle and thereby unnest the surface area-increasing patterns of adjacent sheets. The expanded, unshingled bundle thus forms all or a part of the fill pack in the liquid cooling apparatus.
Film type fill media in the form of a fill pack has been used for many years in liquid cooling apparatus such as water cooling towers. Film type media generally takes the form of a large number of individual film fill sheets configured and oriented to present both a liquid path and a fluid cooling medium path therebetween with each sheet of the pack providing a relatively large surface area over which the hot liquid being cooled spreads into a relatively thin film, on opposite faces of each of the sheets. A coolant fluid such as cool ambient air is then drawn over the large surface area of the liquid film causing the liquid to be cooled by direct contact of the coolant fluid with the hot liquid. In the case of hot water, the water is cooled evaporatively. The individual fill sheets are generally fabricated of a flexible material such as a synthetic resin and are therefor not capable of standing by themselves when formed into a pack. Two methods of supporting film fill type media are commonly used to install film fill packs in cooling towers.
One method of providing support is to glue a plurality of film fill sheets into requisite packs and to support the fill packs by stacking them on underlying structural supports. By gluing the film fill sheets together at discrete contact points, a lattice type structure is developed which thereby contributes substantial strength to the overall pack. Gluing of the sheets is especially useful in fabrication of fill packs made up of cross-corrugated film fill media. An exemplary cross-corrugated fill pack is disclosed by Munters in U.S. Pat. No. 3,415,502 (Liquid and Gas Contact Body). A major disadvantage of the gluing method is the fact that cross-corrugated film fill packs inherently are dominated by air voids. Pack gluing usually takes place in a factory. This makes for inefficient shipping as most of the pack is air and the packs must be handled multiple times during shipment and installation.
Mobile pack-making machines have been used at the site of very large towers to overcome the shipping disadvantage. Nested film fill sheets with little or no air voids and glue are shipped to the location of the mobile pack-making machine near the tower under construction where the packs are made. Pack fabricating equipment, however, is very expensive, requires set-up at and then removal from the point of usage, and necessitates the provision of weather protection structure for the equipment.
Mobile pack making is expensive not only because of the capital costs incurred, but also because it is necessary to hire a crew, train that crew, prepare a staging area, and to purchase insurance, obtain permits, etc. which makes it economical for only very large towers and then only for certain favorable ambient conditions. Total handling and installation costs are thus about the same as for factory made packs.
A second common method of installing fill in cooling towers is to hang a plurality of film fill sheets making up a pack from support tubes carried by frame work of the tower. Support tube openings are provided near the top of each of the fill pack film sheets. The sheets are then suspended one at a time from the support tubes placing the sheets in tension except for the very top portion of each sheet. Exemplary film fill sheets used to fabricate fill packs hung from support tubes in water cooling towers are disclosed by Kinney, Jr. et al. in U.S. Pat. Nos. 4,548,766 (Vacuum Formable Water Cooling Tower Film Fill Sheet with Integral Spacers), 4,826,636 (Multi-Level Film Fill Industrial Cross Flow Cooling Tower), and 4,801,410 (Plastic Fill Sheet for Water Cooling Tower with Air Guiding Spacers) and by Bugler et al. in U.S. Pat. No. 5,147,583 (Non-Clogging Film Fill Assembly for Counterflow Water Cooling Tower).
Adjacent film fill sheets must contact one another to keep the sheets properly spaced and to minimize aerodynamically excited vibrations. In cross-corrugated fills as illustrated and described in the ""502 patent, and non-clogging film fill as shown and described in the ""583 patent, sheet contact is necessary to force the air to repetitively split and regroup, thus mixing the air as it traverses through the fill pack. Additionally, the integral louvers, integral eliminators, and air guiding spacers such as shown and described in the ""410 patent form cellular or honeycomb structures, which necessarily require contact by adjacent sheets.
Two film fill surface configurations are generally employed to obtain requisite contact between the cooling fluid medium and the hot liquid within the fill pack. One surface configuration is such that sheets which are nested for shipment may be alternately rotated or flipped over when forming the pack therefrom. Exemplary fill sheets in this respect are found in the ""502 and ""583 patents. This surface area-increasing geometry has the advantage that all of the sheets are the same.
Another method is to simply make two different complemental sets of film fill sheets which are alternated in the installation, i.e., A, B, A, B, etc. An exemplary fill using film fill sheets of this technique is discussed and illustrated in U.S. Pat. No.9,320,073.
Both of these methods require extensive handling of the individual film fill sheets to orient the sheets properly to form the desired pack. For shipping purposes, in order to avoid the problem of shipping film fill packs in assembled condition, which is largely air, the fill pack is assembled on site. In the case of hanging fill packs, one sheet at a time must be placed on the support tubes. This means that the installers must remove individual film fill sheets which have been shipped nested, one at a time from the packing crate. These film fill sheets are then elevated to the point of installation where they are sequentially placed over support tubes in proper orientation one with respect to another. Obviously, in view of the flexibility of the film material and the overall area of each of the film fill sheets, wind velocities are a major factor in the construction process. In fact, film fill sheet installation must be halted when the wind velocity exceeds a value determined and established as a standard by experience.
To save hanging fill pack erection time at the tower site, there has been an effort to glue the film fill sheets into packs at ground level prior to installation on the tube supports. This is expensive, as previously pointed out, and can only be justified on short construction schedules.
Therefore, what is needed and has not been previously available is a multiple sheet film fill that (a) ships with nested sheets to the assembly or construction site to minimize shipping costs by avoiding shipping of air, (b) minimizes handling of individual sheets during the fill installation in the tower, and (c) avoids the expense of gluing of the sheets one to another on site.
In particular, this unfulfilled need is now satisfied by the provision of a bundle made up of a number of liquid film fill sheets in which every other sheet is shingled in order to permit the sheets to be nested for shipping. Each of the film fill sheets has area-increasing surface patterns on opposite faces thereof. The surface patterns of the film fill sheets are configured for complemental nesting of adjacent overlying sheets when adjacent sheets are offset relative to the other sheets to present the shingled fill sheet bundle. The shingled bundles may each be raised as a unit to fill support elevation. Each bundle of film fill sheets is then inserted on support structure such as support tubes. Individual film fill sheets of each bundle may be sequentially separated in place, one from another, starting at one end of the bundle to expand the bundle and unnest the sheets while the bundle is supported by the fill support structure. The expanded bundle thus forms a part or all of the fill pack.
In a preferred embodiment of the invention, all of the sheets of the shingled bundle have primary openings which are aligned for receipt of the supporting structure for the fill pack. The sheets that are offset to present the shingled bundle each have secondary openings aligned with the primary openings of the remaining sheets of the bundle.
The shingled bundle of film fill sheets is adapted to first be mounted on the support structure therefor in disposition with the support structure extending through the primary openings of the unshingled sheets of the bundle, and through the secondary openings of the shingled sheets. Each of the sheets provided with secondary openings has slots therein extending from respective secondary openings to the primary openings in corresponding sheets.
Expansion of the bundle of film fill sheets is accomplished by the simple expedient of sequentially unshingling the shingled sheets as the slots in those sheets clear the supporting structure. The slots in the offset sheets permit these sheets to be individually shifted as respective slots clear the support tubes to unnest adjacent sheets, thus allowing all of the sheets to be moved into aligned, unnested relationship, presenting the desired section of the final fill pack. In view of the fact that a relatively large number of film fill sheets may be placed in overlying, shingled, nested relationship defining a bundle, it is apparent that only a limited number of the individual bundles must be raised from ground level to fill elevation in order to permit fabrication of a completed fill pack within a defined area of the h cooling apparatus or tower.
In another embodiment of the invention, alternate sheets of the nested, shingled bundle have oppositely inclined slots which cooperate to present support openings for receiving the fill pack support structure to provide initial support for the nested, shingled bundle. The slots also function to clear the support structure as adjacent sheets are shifted relative to each other and with respect to the support structure through a displacement equal to one-half of the width of the repetitive surface area-increasing patterns and thus into unnested, fill-defining relationship as the support structure is then received in aligned openings at opposite ends of adjacent slots.
In a further embodiment of the invention, all sheets of a bundle have the described openings for receiving the fill pack support structure when the bundle is initially mounted on that support structure, but in this instance, every other sheet has an elongated, generally horizontal, L-shaped slot, while alternate other sheets have elongated slots, transverse to the L-slots. Expansion of the shingled bundle is carried out by successive shifting of the sheets with the L-shaped slots therein with respect to the sheets having the transverse slots and relative to the supporting structure. The L-shaped slots clear the support structure as the sheets with the L-slots therein are shifted in a direction along the length of the long leg of the L. The sheet with the L-slot that is shifted, as well as the next adjacent sheet with a transverse slot, then shift together to bring the support structure into the short leg-defining opening of the L-slot of one sheet and toward an opposite end of the transverse slot in the other proximal sheet to lock the last shifted sheets to the support structure with adjacent surface area-increasing patterns in unnested relationship.
In a still further embodiment of the invention, every other sheet of the shingled bundle is offset from an adjacent sheet in two directions. In this instance, the surface area-increasing patterns of the individual sheets are in checkerboard relative disposition, in which the patterns in adjacent sheets of respective rows nest when the offset sheets of the bundle are displaced from the other adjacent sheets in two directions, i.e., both laterally and in an upright direction when the bundle is mounted on the support structure for the fill assembly. Each of the offset sheets of the shingled bundle has an inclined slot which extends from the aligned openings of the shingled bundle which receive the support tubes for the fill when a bundle is first mounted on the support tubes at fill elevation, and which clear the support tubes as respective offset sheets are shifted both laterally and in a generally upright path to effect successive expansion of the bundle and unnesting of the sheets.
The film fill sheets are preferably of relatively thin, flexible material and the slots which interconnect the primary and second openings of each of the shingled sheets of the nested bundle thereof comprise relatively narrow slits which permit the support structure for the pack to pass therethrough as the film material flexes during unshingling of the initially shingled sheets.
The film fill sheets preferably each have repeating area-increasing surface patterns on opposite faces thereof. In an illustrative case where the patterns are A-B, A-B, etc., pattern A of each sheet is configured to nest with pattern A of another sheet. The same is true with respect to pattern B, etc. The effective dimension of each of the different patterns in the direction of A-B, A-B, etc., is therefore preferably the same. When the film fill sheets are nested, pattern A, for example, is at the top, or to one side of a sheet, while pattern B is at the top or to that one side of the next-adjacent film fill sheet of the nested bundle. Therefore, the extent of offset of every other film fill sheet in the shingled bundle thereof is equal to the width of respective surface patterns, with the A patterns of each sheet being nestable in a corresponding A pattern of adjacent sheets. The same is true as to B patterns.
The invention, however, is not restricted to A-B surface area-increasing patterns as described. The patterns could be A-B-C, etc. The only requirement is that the patterns of adjacent sheets nest, and the bundle of nested sheets may be successively and sequentially unnested while carried by support structure therefor to form the fill pack or fill pack section. Similarly, the fill patterns may present a checkerboard arrangement as described, in which case adjacent nested sheets are offset from one another in two directions.
The nested, expandable, liquid film fill sheet bundle hereof has utility in various applications, including crossflow and counterflow water cooling towers, or evaporative heat transfer apparatus using film fill such as waste heat air saturators, evaporative condensers with fill, and fluid coolers with fill.